Process and apparatus for producing seamless cellulose tubes



P .9, w. 'SCHWALBE ET AL 1,997,349

PROCESS AND APPARATUS FOR PRODUCING SEAMLESS CELLULOSE TUBES Filed Dec. 5, 1933 Patented Apr. 9, 1935 PATENT OFFlCE rnocass AND mam'rus ron monocmo snsmss GELLULOSE runes Waldemar- Schwalbe and baden-Biebrich, Germany,

Corporation, Chicago, 111., a corpora- Virginia Visking vtion of Application out Schnecko, Wiesassignors, to The December 5, 1933, Serial in. 161,010

In Germany December 22, 1932 40laims.

The present invention relates to the manufacture of seamless cellulose tubes, produced, for example, from viscose solutions.

The primary object is to provide an improved process 01' manufacture which involves maintaining the tube in inflated condition during substantially all of the period or time while the viscose is undergoing regeneration, that is, be ing converted to cellulose.

The viscose solution may be extruded through an annular nozzle upwardly through a coagulating and regenerating bath in a known manner. The present invention contemplates, however, the carrying of the tube in inflated condition not only through the extrusion bath but also through subsequent baths until the regeneration is complete. Thereafter, the tubing may be wound ,in flattened condition upon a take-up roll, preferably after having been purified by suitable washings; or it may be conducted, still in an inflated condition, through suitable drying apparatus.

In accordance with the invention as preferably practiced, gases generated within the tube which is being drawn are permitted to escape rearwardly through a drainpipe which extends downwardly through the inner extrusion-membcr of the extruding-device, this drain-pipe serving also to permit escape of overflow from the internal bath.

The invention may be practiced by means of any preferred apparatus. The accompanying drawing illustrates diagrammatically apparatus which may be used in the practice of the process. In the drawing:--

Fig. 1 is a broken vertical sectional view oi apparatus adapted to practice of the process; Fig. 2, an enlarged broken vertical section of the lower part of the extrusion-tank and the ex trusion-device connected therewith; and Fig. 3,

an elevational view of one of a series oi drums which serve to carry the extruded tubing through a series 01 baths.

Referring to the drawing, A designates an extrusion-tank which contains an external bath, indicated at I, this bath preferably consisting of a solution of a suitable coagulating compound and a suitable regenerating compound; B, an extrusion-device mounted in the tank and ,extending through the bottom thereof, said extrusion-device having associated therewith a tubular mandrel B having a base-portion l? fitted with a plug 3* from which depends a drain-pipe B which extends downwardly through 55 the inner member or the extrusion-device and is equipped'at its lower end with a trap B; C, an admission-pipe through which the external bath is admitted to the lower portion of the tank; D, a viscose-admission pipe which leads to the .space between the inner and outer extrusionmembers of the device B, in a known manner; E, an admission-pipe through which a suitable coagulating and regenerating fluid is admitted to the space between the drain-pipe and the inner member of the extrusion-device, so that this internal bath may be delivered into the space between the mandrel and the viscose tube; F, a viscose tube which issues from the annular extrusion-orifice oi the device B and passes in inflated condition through the several baths; G, a series of regenerating baths in which the final stages of regeneration may be completed; H, a bath in which the cellulose tube may be washed; 1, a bath through which the purified tube may be passed, this bath containing, if desired, a small percentage of glycerine; J, a takeup roll upon which the tubing is wound in flat condition; K, a series of drums upon which the tubing F is carried over and through the several baths; and M, M, guide-devices'associated with the drums.

The tube F is shown as passing upwardly out 01 the tank A and about a grooved roller L from which it passes to the first drum. Preferably, the roller L and the drums are of large diameter and are suitably geared togetherand given a proper rate of rotation with relation to the desired speed of extrusion.

The. guide-devices M and M may be any suitable devices for causing the tube F to form a spiral on the drum as the tube is drawn onto the drum. In the form shown, each guide-device comprises a cross-bar 2 which supports a series of guide-fingers 3, which are suitably arranged and spaced to cause the tube to be wound, threadlike, upon the drum; The drums dip into the baths. If desired, they maybe wholly immersed in the baths; or, if desired, regenerating fluid may be sprayed upon the tube F while it is being fed forwardly by the drums. Any suitable form of carriers which will serve to maintain the tubing in inflated conditions while it is undergoing regeneration may be substituted for the apparatus, shown. Y

The drain-tube B has its upper end extending through theplug l3 and opening into the main portion B of the mandrel. The position of the upper end of the mandrel determines the height of the internal bath which should corequipped with a drain-tube I.

By reference to Fig. 2, it will be noted that the trap B is in the form of a cup which has threaded connection with the lower end of the drain-tube B The trap is provided with overflow openings 5 which are disposed above the lower end of the drain-pipe. Thus, the lower end of the drainpipe may extend into the trapped solution, so as to maintain a desired moderate pressure within the tubing F. Anyexcess of gas above the gas required to maintain the desired moderate pressure is permitted to escape through the openings 5. In the beginning of the extrusion operation, after the tubing F hasbeen led upwardly and forwardly for a certain distance, amoderate amount of air-pressure may be supplied to keep the tubing in distended condition until the action of the acid in the regenerating bath creates suflicient internal pressure to maintain the tubing in inflated condition. I

The process described avoids injury to the tubing and permits escape of gases generated within the tubing undergoing regeneration; and by pernitting gases to escape in this manner, it becomes unnecessaryto resort to slitting of the tubing F from time to time to permit escape of gases. Thus, the improved process results in effecting a very considerable saving of tubing and serves to expedite the drawing process.

Where the tubing is wound in flat condition upon a take-up roll, the tubing may subsequently be conducted from the take-up roll through a suitable drying apparatus, and may be maintained in inflated condition during the drying operation. A method for maintaining an elongated body of air within the portion of the tubing undergoing drying is well known, and is not claimed herein.

In the early part of the extrusion operation, or at any othertime, if necessary or desirable, air may be injected through the trap B into the viscose tubing. 1

It may be stated, with reference to the series of baths employed, that, any desired number of baths may be employed for any desired purpose.

It is quite common, for example, to use 'a series of baths which include a regenerating bath, a series of baths containing heated water, graduated in temperature, if desired, and a flnal bath containing a hygroscopic agent, such as glycerin.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

What we claim as new and desire to secure by Letters Patent is:

l. A process of producing seamless tubes from cellulose solutions, which comprises: extruding the solution in the form of a tube into a coagulating and regenerating bath and carrying the extruded tube, in inflated condition, through said bath and through a succession 0! baths, and permitting the gases generated within the extruded tube to escape rearwardly through the extrusiondevice, whereby slitting oi the tube at intervals is rendered unnecessary.

2. A process as set forth in claim 1, in which the extruded tube, after passing through a series of baths containing regenerating solution, passes through a purifying bath.

3. A process as stated in claim 1, in which the tube, after passing through the regenerating baths and a purifying bath, is subjected, while still in an inflated condition, to a drying operation.

4. Apparatus for formingcellulose tubes, which comprises: an extrusion-tank having fitted to its bottom an extrusion-device through which seamless tubing may be extruded upwardly into said tank; means for supplying coagulating and regenerating fluid as an external bath in said tank and as an internal bath within the tubing being extruded; vent-means in said extrusiondevice for controllinginternal gas pressure in said tubing; a series of additional treating tanks; and means for carrying the extruded tubing in inflated condition from the point of extrusion through the extrusion-bath and the succeeding baths.

WALDEMAR SCHWALBE.

O'I'IO SCHNECKO. 

